The non-slotted plate is the newest thing, at least on the stock Cockers, and has become pretty popular. Yes, with a slotted plate and a flattened rod you'll be taking up a lot more slack than with a slotted plate and a normal round rod... I belive there's still a BIT of slack.
Have you seen the non-slotted plates and the round rods? There's next to no slack, if any. It's a bit more fickle and requires being re-timed a bit more often, if I recall correctly, but that's really not a big deal to me.
Take a look at a Stock 2000+ cocker or a STO... or a Shocktech Cocker... anything like that. I can take pics of mine for you if you'd like, but it's not completely stock.
That's the new Shocktech trigger plate with the non-slotted "hole."
That clear things up? Otehrwise, like I said, I can take pics of my frame.